Space balls…

These are supposedly a great puzzle to Vietnam’s defense ministry, but they should not be. The spherical shape tells you that the metal balls contained something, probably a gas, which was under pressure, because that shape is the strongest possible for containing anything under pressure.

You would find these on a variety of airplanes, so they were likely jettisoned or dropped. They could also be space junk from rockets, but my friends who know something about aviation mechanics say the first explanation is the more probable.